The catalase and superoxide dismutase genes are transcriptionally up-regulated upon oxidative stress in the strictly anaerobic archaeon Methanosarcina barkeri

Abstract

Methanosarcina barkeri is a strictly anaerobic methanogenic archaeon, which can survive oxidative stress. The oxidative stress agent paraquat (PQ) suppressed growth of M. barkeri at concentrations of 50-200 mM. Hydrogen peroxide (H 2 O 2 ) inhibited growth at concentrations of 0?4-1?6 mM. Catalase activity in cell-free extracts of M. barkeri increased about threefold during H 2 O 2 stress (1?3 mM H 2 O 2 , 2-4 h exposure) and nearly twofold during superoxide stress (160 mM PQ, 2 h exposure). PQ (160 mM, 2-4 h exposure) and H 2 O 2 (1?3 mM, 2 h exposure) also influenced superoxide dismutase activity in cell-free extracts of M. barkeri. Dot-blot analysis was performed on total RNA isolated from H 2 O 2 -and PQ-exposed cultures, using labelled internal DNA fragments of the sod and kat genes. It was shown that H 2 O 2 but not PQ strongly induced up-regulation of the kat gene. PQ and to a lesser degree H 2 O 2 induced the expression of superoxide dismutase. The results indicate the regulation of the adaptive response of M. barkeri to different oxidative stresses.

Desiccation as a Long-Term Survival Mechanism for the Archaeon Methanosarcina barkeri

“…Recent reports on tolerance of Methanosarcina spp. to stress indicate that these species have enzymes for protection from oxidative stress and repair of DNA damage resulting from ionizing radiation and the ability to endure short periods of desiccation (7,21,33,47). The Methanosarcina morphology of multicellular aggregates embedded in an EPS matrix is unique among the methanogens, and it is remarkably similar to the morphology of other desiccationresistant prokaryotes.…”

Subunit D of RNA Polymerase from Methanosarcina acetivorans Contains Two Oxygen-labile [4Fe-4S] Clusters

“…Because M. acetivorans is a strict anaerobe and exposure to oxygen shuts down metabolism (17,43), one possible mechanism to globally conserve energy to maintain critical functions during times of iron depletion or oxidative stress would be to decrease production of RNA to minimum levels adequate for cellular maintenance. The lack of cluster incorporation, the oxidation of the clusters, or oxidative loss of incorporated clusters within domain 3 of subunit D may prevent the de novo assembly of RNAP.…”

Alkaliphilic bacteria: applications in industrial biotechnology

“…Hence, organisms produce antioxidants in the form of enzymes and other molecules to reduce the levels of ROS [254]. Catalase (EC 1.11.1.6) is an anti-oxidant biocatalyst facilitating conversion of H 2 O 2 to O 2 and H 2 O [37], and is produced in response to oxidative stress or due to presence of ROS [45].…”